Processing of acoustic information varies with place along the cochlear partition and it appears that this processing is itself subject to ontogenetic change. We propose 4 interrelated projects that deal with different facets of this central theme. 1. Project 1 asks whether the place of analysis at the basal turn changes its responsiveness ontogenetically. 2. Project 2 asks whether the place code changes as a result of insult --- is it plastic? 3. Project 3 asks whether the efferent transmitter differs according to place and seeks to define its actions according to place along the partition. 4. Project 4 asks whether psychophysical performance of normal humans changes according to place along the partition.